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Outcomes following single-level lumbar fusion in patients with myasthenia gravis
, Clare K. Greenb, Joyce En-Hua Wangb, Ved A. Vengsarkarc, Wendy Novicoffb, Xudong Lib, Stephen Lockeyb,
⁎Corresponding author: Stephen Lockey. ymw9ny@uvahealth.org
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Received: ,
Accepted: ,
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Abstract
Patients with myasthenia gravis (MG) are at higher risk for postoperative complications after surgery. Knowledge concerning the impact of the condition on outcomes and complications after spine surgery is currently limited. Using a large-scale, national database, the purpose of this investigation was to compare the rate of medical and surgical complications, healthcare utilization, and need for revision surgery following single-level lumbar fusion between patients with and without MG.
Data was collected using the PearlDiver database and adult patients with and without MG who underwent single-level lumbar spine fusion from 2010 to 2022 were matched 1:4 on age, sex, and baselin comorbidities. Pearson's Chi-squared test and Welch's t-test were used to evaluate differences in demographic and clinical outcomes. Univariate analysis and multivariate logistic regression were performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) after controlling for potential confounders.
A total of 537 (20.0%) patients with MG were matched with 2140 (80.0%) patients controls. At 90 days postoperatively, patients with MG experienced significantly higher rates of postoperative arrhythmia, cerebrovascular accident, atelectasis, respiratory failure, pleural effusion, pulmonary embolism, urinary retention, urinary tract infection, and renal failure. At two-year follow up, 27 (5.0%) patients with MG developed pseudoarthrosis compared to 48 (2.2%) controls (OR 2.32; 95% CI: 1.41-3.74; p < 0.001), and 38 (7.1%) MG patients had undergone revision lumbar spine surgery compared to 61 (2.9%) controls (OR: 2.61; 95% CI: 1.70-3.95; p < 0.001). Regarding healthcare utilization, patients with MG were more likely to present to the emergency department and require readmission at both 30 and 90 days postoperatively.
Patients with MG experienced more postoperative complications and higher healthcare utilization after single-level lumbar fusion. These findings highlight the importance of individualized perioperative planning to mitigate risks and inform surgeon counseling of patients and their families.
Keywords
Lumbar fusion
Myasthenia gravis
Healthcare utilization
Postoperative complications
Retrospective cohort study
Spine surgery
1 Introduction
Myasthenia gravis (MG) is an autoimmune disorder characterized by defective transmission at the neuromuscular junction, resulting in fatigable muscle weakness.1 The clinical presentation of MG is widely variable, ranging from mild ocular involvement to severe weakness of the bulbar, limb, and respiratory muscles.2 The annual incidence of MG in the United States continues to rise, with a reported rate of 68.5 per million person-years as of 2024.3 However, advancements in treatments have significantly reduced associated morbidity and improved life expectancy.4,5 Consequently, as this patient population ages so does the likelihood of developing degenerative lumbar spine pathology that may require surgical treatment.
It is well established that MG is known to increase the risk of complications after surgery.6 Approximately 13-22% of MG patients also have a second autoimmune condition, and are often immunosuppressed, which compounds the risk of adverse outcomes.7 Multiple perioperative factors, including the type of surgery, pain control, and fatigue have been linked to an exacerbation of the condition leading to myasthenic crisis.8,9 Patients with MG experience greater perioperative risks from anesthesia due to muscle weakness and possible interactions with medications used to treat the condition.10 Sherman et al. investigated the impact of MG on outcomes following total hip and knee arthroplasty. The authors found that patients with MG experienced higher rates of postoperative pneumonia, respiratory failure, sepsis, and surgical site infections.1,11 At present, the impact of MG on outcomes following spine surgery remains poorly described, with current published data limited to isolated case reports 11–14.
Given that the number of patients with MG requiring spine surgery is likely to rise, it is important to understand the perioperative risks associated with the condition. Using a large national healthcare database, this study aimed to compare postoperative complications and outcomes following single-level lumbar spine fusion between patients with and without the disease. The central hypothesis of this investigation was that MG would be associated with significantly higher rates of medical and surgical complications as well as postoperative healthcare utilization and need for revision compared to controls.
2 Materials and methods
2.1 Data source
Subject data were obtained from the M170 Ortho dataset in the multipayer database PearlDiver (PearlDiver Inc., Colorado Springs, Colorado, USA), which contains claims records for over 170 million patients. The database is searchable by International Classification of Diseases (ICD) and Current Procedural Terminology (CPT) codes. Patient records are deidentified in the PearlDiver database and deemed Health Insurance Portability and Accountability Act (HIPAA)-compliant, so the study was exempt from the Institutional Review Board approval process.
2.2 Study population
Patients who underwent a primary single-level lumbar fusion were identified from 2010 to 2022. Patients were stratified by a prior diagnosis of MG using ICD-9/10 codes. Exclusion criteria included multi-spinal level procedures, patients younger than 18 years of age, or those with a prior history of metastases, trauma, and/or infection to the spine within 90 days prior to or on the day of the procedure. Baseline characteristics, such as age, sex, Elixhauser Comorbidity Index (ECI), obesity, and tobacco use were determined. Patients diagnosed with MG were identified and matched in a 1:4 ratio to controls without MG based on age, sex, and relevant baseline comorbidities to account for potential confounders.
2.3 Outcomes
Outcomes of interest were 90-day medical complications, including arrhythmia, myocardial infarction, cerebrovascular accident (CVA), atelectasis, respiratory failure, pleural effusion, pulmonary embolism (PE), urinary retention, urinary tract infection (UTI), renal failure, sepsis, wound infection, spinal cord deficit, nerve root motor deficit, and nerve root sensory deficit. Two-year complications included pseudarthrosis, revision, and mortality. Healthcare utilization metrics, such as 30-day and 90-day emergency department (ED) visits and inpatient readmission were also assessed.
2.4 Statistical analysis
All statistical analyses conducted for this study were performed using the research query software provided by PearlDiver Bellwether. The R statistical package in PearlDiver Bellwether was used for common statistical measures such as frequencies, mean values, and odds ratios. Statistical significance was set to p < 0.05. For assessing differences in patient demographics and co-morbid conditions, Pearson x2 test and Welch's t‐test were selected. Univariate analysis was used to identify statistically significant post-operative outcomes and surgery complications. Multivariable logistic regression was performed on the variables identified as significant from the univariate analysis while controlling for demographics and co-morbidities.
3 Results
A total of 347,741 patients who underwent lumbar fusion procedures and met inclusion criteria were identified. From this cohort, 537 (20.0%) patients with MG were matched with 2140 (80.0%) patients without the disease. There were no significant differences in age, sex, ECI, BMI, or smoking history between the two matched groups (p > 0.05 for all) (Table 1).
| Unmatched n = 85,198 | Matched n = 569 | |||||||||
| MG n = 122 | No MG n = 85, 076 | p-value | MG n = 115 | No MG n = 454 | p-value | |||||
| Age | 63.3±10.8 | 59.9±12.7 | <0.001∗ | 63.8±10.4 | 63.6±10.5 | 0.862 | ||||
| Sex (Female) | 65 | 53.3% | 49,091 | 57.7% | 0.370 | 60 | 52.2% | 235 | 51.8% | 1.000 |
| Comorbidities | ||||||||||
| ECI | 7.0±4.6 | 3.5±3.7 | <0.001∗ | 6.5±4.2 | 6.4±4.1 | 0.705 | ||||
| BMI 30-40 | 25 | 20.5% | 8026 | 9.4% | <0.001∗ | 22 | 19.1% | 87 | 19.2% | 1.000 |
| BMI 40+ | 10 | 8.2% | 3012 | 3.5% | 0.011∗ | 5 | 4.3% | 17 | 3.7% | 0.977 |
| Smoke | 30 | 24.6% | 13,139 | 15.4% | 0.008∗ | 27 | 23.5% | 105 | 23.1% | 1.000 |
The MG cohort experienced significantly higher rates of medical and surgical complications after surgery (Table 2). Postoperative arrhythmia was the most reported medical complication at 90 days after lumbar fusion (20.7% vs. 9.4%; p < 0.001). The multivariate analysis demonstrates that having MG was independently associated with a significantly higher rate of CVA (p < 0.001), atelectasis (p < 0.001), respiratory failure (p < 0.001), pleural effusion (p < 0.001), PE (p = 0.005), urinary retention (p = 0.030), UTI (p < 0.001), and renal failure (p = 0.010). There were no significant differences in rates of myocardial infarction or sepsis between the two groups. With regard to surgical complications, there were no observed differences between groups for rates of nerve root motor or sensory deficits, spinal cord deficits, or wound infections. At two-year follow-up, 38 (7.1%) patients in the MG cohort had undergone a revision procedure compared to 61 (2.9%) of controls (OR: 2.61; 95% CI: 1.70-3.95; p < 0.001). In addition, MG patients were significantly more likely to develop pseudoarthrosis compared to patients without the disease at two-year follow-up (OR 2.32; 95% CI: 1.41-3.74; p < 0.001).
| MG n = 115 | No MG n = 454 | Univariate p-value | Multivariate Adjusted OR (95% CI) | Multivariate p-value | |||
| Medical | |||||||
| Arrhythmia | 20 | 17.4% | 45 | 9.9% | 0.037∗ | 2.03 (1.08 - 3.72) | 0.024∗ |
| Myocardial infarction | 2 | 1.7% | 6 | 1.3% | 0.666 | – | – |
| CVA | 3 | 2.6% | 5 | 1.1% | 0.207 | – | – |
| Atelectasis | 7 | 6.1% | 11 | 2.4% | 0.088 | – | – |
| Respiratory Failure | 4 | 3.5% | 6 | 1.3% | 0.123 | – | – |
| Pleural Effusion | 6 | 5.2% | 2 | 0.4% | 0.001∗ | 13.39 (2.97 - 93.61) | 0.002∗ |
| PE | 2 | 1.7% | 4 | 0.9% | 0.350 | – | – |
| Urinary Retention | 2 | 1.7% | 7 | 1.5% | 1.000 | – | – |
| UTI | 14 | 12.2% | 30 | 6.6% | 0.072 | – | – |
| Renal Failure | 11 | 9.6% | 24 | 5.3% | 0.137 | – | – |
| Lumbar Spine Infection | 5 | 4.3% | 15 | 3.3% | 0.795 | – | – |
| Surgical | |||||||
| Nerve Root Motor Deficit | 8 | 7.0% | 8 | 1.8% | 0.007∗ | 4.74 (1.63 - 13.91) | 0.004∗ |
| Nerve Root Sensory Deficit | 1 | 0.9% | 3 | 0.7% | 1.000 | – | – |
| Pseudarthrosis (2y) | 3 | 2.6% | 10 | 2.2% | 0.732 | – | – |
| Revision (2y) | 16 | 13.9% | 18 | 4.0% | <0.001∗ | 4.09 (1.97 - 8.43) | <0.001∗ |
In terms of healthcare utilization, patients with MG were more likely to present to the ED within the first 30 (OR: 3.78; 95% CI: 2.89-4.94; p < 0.001) and 90 days (OR: 4.03; 95% CI: 3.19-5.08; p < 0.001) postoperatively. Similarly, MG patients were more likely to be readmitted at 30 days (OR: 4.01; 95% CI: 3.02-5.32; p < 0.001) and at 90 day follow-up (OR: 4.70; 95% CI: 3.65-6.07; p < 0.001) (Table 3).
| MG n = 115 | No MG n = 454 | Univariate p-value | Multivariate Adjusted OR (95% CI) | Multivariate p-value | |||
| ED visit (30d) | 17 | 14.8% | 13 | 2.9% | <0.001∗ | 6.41 (2.97 - 14.23) | <0.001∗ |
| ED visit (90d) | 22 | 19.1% | 17 | 3.7% | <0.001∗ | 6.59 (3.32 - 13.35) | <0.001∗ |
| Inpatient readmission (30d) | 39 | 33.9% | 40 | 8.8% | <0.001∗ | 5.70 (3.39 - 9.66) | <0.001∗ |
| Inpatient readmission (90d) | 48 | 41.7% | 50 | 11.0% | <0.001∗ | 6.31 (3.87 - 10.38) | <0.001∗ |
| Mortality (2y) | 0 | 0.0% | 0 | 0.0% | – | – | – |
4 Discussion
Myasthenia gravis is an autoimmune disorder characterized by fluctuating muscle weakness.2 While advances in treatment have significantly reduced disease burden and extended life expectancy, the systemic nature of MG still presents challenges in the perioperative setting.6,15,16 This study found that patients with MG experience higher rates of postoperative complications compared to age-matched controls. These findings mirror reported outcomes in MG patients following surgery for other conditions.1,6,11,13 For example, patients with MG have been shown to experience higher rates of respiratory complications, infections, and prolonged hospitalization following thymectomy.13 Specific to orthopaedic surgery, Sherman et al. reported higher rates of pneumonia, reintubation, and sepsis following total hip and knee arthroplasty in patients with MG.1 Similarly, Cichos et al. observed increased risk of prosthetic complications, infections, and MI following total joint replacement in patients with MG.11
The results of this study indicate that patients with MG may be at increased risk of cardiopulmonary issues after lumbar fusion. Pleural effusions are an uncommon respiratory complication following lumbar spine surgery, with a reported rate of 1.6% in the literature.17 The increased incidence observed in this study may reflect underlying respiratory muscle weakness inherent to patients with MG, which is then exacerbated by the physiologic stress of surgery and postoperative immobility 2,15–17. Of note, prior investigations have reported elevated rates of postoperative atelectasis and respiratory failure in patients with MG which were not observed in this study.13 Patients with MG also experienced higher rates of postoperative arrhythmia compared to controls. Prior studies have demonstrated MG to be an independent risk factor for cardiac arrhythmia.18 While the mechanism behind this association is not fully understood, several studies have suggested that this predisposition may be the result of autonomic dysfunction rather than abnormalities inherent to the conduction system.19 Altogether, these findings underscore the importance of careful counseling, close monitoring, and multidisciplinary management for patients with MG in the perioperative setting.
Patients with MG were also significantly more likely to require revision at two years postoperatively when compared to the control group. This finding is similar to reported outcomes following total joint arthroplasty in patients with the disease.1,11 There are likely several factors contributing to higher revision rates in patients with MG. Baseline deconditioning and increased risk of obesity among those with MG may predispose patients to complications that require additional surgery.20,21 Additionally, glucocorticoids are commonly prescribed for the treatment of MG and are known to have detrimental effects on bone health.22 Although the introduction of newer biologic therapies has reduced the use of glucocorticoids, steroid-associated osteoporosis remains a significant concern.23 Patients with osteoporosis undergoing lumbar fusions are known to be at elevated risk for a range of postoperative complications that may require additional procedures to address adjacent segment disease, hardware failure, and proximal junctional kyphosis. The potential impact on bone health from the associated treatment of MG may explain the increased risk of revision observed in the study cohort 23–26.
Finally, the results of this study suggest that patients with MG experience higher rates of healthcare utilization following lumbar fusion procedures. This observation may be related to the development of postoperative complications or existing disease burden exacerbated by the physiologic stress from undergoing surgery. Surgical procedures and systemic infections can provoke the onset of myasthenia crisis, which requires acute care evaluation and management.27,28 While rates of postoperative readmissions in this population have not been previously reported, these findings are consistent with prior studies demonstrating increased healthcare utilization in patients with MG undergoing other surgical procedures.1,11,13,29 Hospital readmissions also represent a significant financial burden and may diminish the overall cost-effectiveness of lumbar fusion in this population. Collectively, these findings highlight the importance of careful discharge planning and may aid surgeons in appropriate preoperative counseling of patients and their families.
There are several important limitations to note in this study. The reliance on ICD and CPT coding may have led to misclassification. MG is a diverse condition, with considerable variation in muscle weakness, bulbar and respiratory symptoms, and treatment response. This variability within the patient population may influence outcomes and confound interpretation of the results. Another limitation of the study is a lack of granular clinical detail and radiographic information. As a result, it was not possible to assess patient-reported outcomes or baseline lumbar pathology severity between the two groups. Given that MG can lead to muscular weakness and subsequent deformity, such as camptocormia, it is possible that these patients required more invasive procedures, which may further confound the results. Lastly, the PearlDiver database draws primarily from certain insurance providers. Consequently, the results of the study may inherently involve geographic or payer-specific biases that can skew outcomes and limit the generalizability of results.
5 Conclusion
The results of this study suggest that patients with MG are at increased risk for postoperative complications, readmission, and need for further surgery compared to a matched cohort of patients without MG following single-level lumbar fusion. These findings highlight the importance of individualized perioperative planning to mitigate risks and should aid surgeons in the appropriate counseling of patients and their families in the perioperative environment.
Patient consent statement
Not applicable.
Guardian/patient's consent
Not Applicable.
Ethical approval
Not applicable.
Ethical statement and consent
This study was exempt from institutional review board approval, as all queried data was deidentified and Health Insurance Portability and Accountability Act (HIPAA) compliant.
Funding statement
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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